GnuPG

GnuPG is a complete and free implementation of the OpenPGP standard as defined by RFC4880 (also known as PGP). GnuPG allows you to encrypt and sign your data and communications; it features a versatile key management system, along with access modules for all kinds of public key directories. GnuPG, also known as GPG, is a command line tool with features for easy integration with other applications. A wealth of frontend applications and libraries are available. GnuPG also provides support for S/MIME and Secure Shell (ssh).

Installation

This will also install pinentry, a collection of simple PIN or passphrase entry dialogs which GnuPG uses for passphrase entry. The shell script /usr/bin/pinentry determines which pinentry dialog is used, in the order described at #pinentry.

Configuration

Directory location

$GNUPGHOME is used by GnuPG to point to the directory where its configuration files are stored. By default $GNUPGHOME is not set and your $HOME is used instead; thus, you will find a ~/.gnupg directory right after installation.

To change the default location, either run gpg this way $ gpg --homedir path/to/file or set the GNUPGHOMEenvironment variable.

Configuration files

The default configuration files are ~/.gnupg/gpg.conf and ~/.gnupg/dirmngr.conf.

By default, the gnupg directory has its permissions set to 700 and the files it contains have their permissions set to 600. Only the owner of the directory has permission to read, write, and access the files. This is for security purposes and should not be changed. In case this directory or any file inside it does not follow this security measure, you will get warnings about unsafe file and home directory permissions.

Append to these files any long options you want. Do not write the two dashes, but simply the name of the option and required arguments. You will find skeleton files in /usr/share/doc/gnupg/. These files are copied to ~/.gnupg the first time gpg is run if they do not exist there. Other examples are found in #See also.

Additionally, pacman uses a different set of configuration files for package signature verification. See Pacman/Package signing for details.

Default options for new users

If you want to setup some default options for new users, put configuration files in /etc/skel/.gnupg/. When the new user is added in system, files from here will be copied to its GnuPG home directory. There is also a simple script called addgnupghome which you can use to create new GnuPG home directories for existing users:

# addgnupghome user1 user2

This will add the respective /home/user1/.gnupg/ and /home/user2/.gnupg/ and copy the files from the skeleton directory to it. Users with existing GnuPG home directory are simply skipped.

Usage

Note: Whenever a user-id is required in a command, it can be specified with your key ID, fingerprint, a part of your name or email address, etc. GnuPG is flexible on this.

Create a key pair

Generate a key pair by typing in a terminal:

$ gpg --full-gen-key

Tip: Use the --expert option for getting alternative ciphers like ECC. [1]

The command will prompt for answers to several questions. For general use most people will want:

the RSA (sign only) and a RSA (encrypt only) key.

a keysize of the default value (2048). A larger keysize of 4096 "gives us almost nothing, while costing us quite a lot"[2].

an expiration date. A period of a year is good enough for the average user. This way even if access is lost to the keyring, it will allow others to know that it is no longer valid. Later, if necessary, the expiration date can be extended without having to re-issue a new key.

your name and email address. You can add multiple identities to the same key later (e.g., if you have multiple email addresses you want to associate with this key).

no optional comment. Since the semantics of the comment field are not well-defined, it has limited value for identification.

Note: The name and email address you enter here will be seen by anybody who imports your key.

Generate a revocation certificate

After generating your key, one of the first things you should do is create a revocation certificate:

$ gpg --gen-revoke --armor --output=revocation_certificate.ascuser-id

This certificate can be used to revoke your key if it is ever lost or compromised.

Warning: Anyone with access to the revocation certificate can revoke your key. Protect your revocation certificate like you protect your secret keys. Print it out, save it on a disk, and store it safely. It will be short enough that you can type it back in by hand without much effort if you just print it out.

List keys

To list keys in your public key ring:

$ gpg --list-keys

To list keys in your secret key ring:

$ gpg --list-secret-keys

Export your public key

gpg's main usage is to ensure confidentiality of exchanged messages via public-key cryptography. With it each user distributes the public key of their keyring, which can be be used by others to encrypt messages to the user. The private key must always be kept private, otherwise confidentiality is broken. See w:Public-key cryptography for examples about the message exchange.

So, in order for others to send encrypted messages to you, they need your public key.

To generate an ASCII version of a user's public key to file public.key (e.g. to distribute it by e-mail):

Use a keyserver

You can register your key with a public PGP key server, so that others can retrieve your key without having to contact you directly:

$ gpg --send-keys key-id

Warning: Once a key has been submitted to a keyserver, it cannot be deleted from the server.[3]

To find out details of a key on the keyserver, without importing it, do:

$ gpg --search-keys user-id

To import a key from a key server:

$ gpg --recv-keys key-id

Warning:

You should verify the authenticity of the retrieved public key by comparing its fingerprint with one that the owner published on an independent source(s) (e.g., contacting the person directly). See Wikipedia:Public key fingerprint for more information.

Using a short ID may encounter collisions. All keys will be imported that have the short ID. To avoid this, use the full fingerprint or long key ID when receiving a key.[4]

Tip:

Adding keyserver-options auto-key-retrieve to gpg.conf will automatically fetch keys from the key server as needed, but this can be considered a privacy violation; see "web bug" in gpg(1).

You can connect to the keyserver over Tor with Tor#Torsocks. Or using the --use-tor command line option. See this GnuPG blog post for more information.

You can connect to a keyserver using a proxy by setting the http_proxyenvironment variable and setting honor-http-proxy in dirmngr.conf. Alternatively, set http-proxy host[:port] in dirmngr.conf, overriding the http_proxy environment variable. Restart the dirmngr.serviceuser service for the changes to take effect.

Encrypt and decrypt

Asymmetric

You need to #Import a public key of a user before encrypting (options --encrypt or -e) a file or message to that recipient (options --recipient or -r). Additionally you need to #Create a key pair if you have not already done so.

To encrypt a file with the name doc, use:

$ gpg --recipient user-id --encrypt doc

To decrypt (option --decrypt or -d) a file with the name doc.gpg encrypted with your public key, use:

$ gpg --output doc --decrypt doc.gpg

gpg will prompt you for your passphrase and then decrypt and write the data from doc.gpg to doc. If you omit the -o (--output) option, gpg will write the decrypted data to stdout.

Tip:

Add --armor to encrypt a file using ASCII armor (suitable for copying and pasting a message in text format)

Use -R user-id or --hidden-recipient user-id instead of -r to not put the recipient key IDs in the encrypted message. This helps to hide the receivers of the message and is a limited countermeasure against traffic analysis.

Add --no-emit-version to avoid printing the version number, or add the corresponding setting to your configuration file.

You can use gnupg to encrypt your sensitive documents by using your own user-id as recipient or by using the --default-recipient-self flag instead; however, you can only do this one file at a time, although you can always tarball various files and then encrypt the tarball. See also Disk encryption#Available methods if you want to encrypt directories or a whole file-system.

Symmetric

Symmetric encryption does not require the generation of a key pair and can be used to simply encrypt data with a passphrase. Simply use --symmetric or -c to perform symmetic encryption:

To decrypt a symmetrically encrypted doc.gpg using a passphrase and output decrypted contents into the same directory as doc do:

$ gpg --output doc --decrypt doc.gpg

Key maintenance

Backup your private key

To backup your private key do the following:

$ gpg --export-secret-keys --armor <user-id> > privkey.asc

Note that gpg release 2.1 changed default behaviour so that the above command enforces a passphrase protection, even if you deliberately chose not to use one on key creation. This is because otherwise anyone who gains access to the above exported file would be able to encrypt and sign documents as if they were you without needing to know your passphrase.

Warning: The passphrase is usually the weakest link in protecting your secret key. Place the private key in a safe place on a different system/device, such as a locked container or encrypted drive. It is the only safety you have to regain control to your keyring in case of, for example, a drive failure, theft or worse.

To import the backup of your private key:

$ gpg --import privkey.asc

Tip:Paperkey can be used to export private keys as human readable text or machine readable barcodes that can be printed on paper and archived.

Edit your key

Running the gpg --edit-key <user-id> command will present a menu which enables you to do most of your key management related tasks.

Note: You will get a warning that the master key was not available and the password was not changed, but that can safely be ignored as the subkey password was.

At this point, you can now use /tmp/subkey.altpass.gpg on your other devices.

Extending expiration date

Warning:Never delete your expired or revoked subkeys unless you have a good reason. Doing so will cause you to lose the ability to decrypt files encrypted with the old subkey. Please only delete expired or revoked keys from other users to clean your keyring.

It is good practice to set an expiration date on your subkeys, so that if you lose access to the key (e.g. you forget the passphrase) the key will not continue to be used indefinitely by others. When the key expires, it is relatively straight-forward to extend the expiration date:

$ gpg --edit-key <user-id>
> expire

You will be prompted for a new expiration date, as well as the passphrase for your secret key, which is used to sign the new expiration date.

Repeat this for any further subkeys that have expired:

> key 1
> expire

Finally, save the changes and quit:

> save

Update it to a keyserver.

$ gpg --keyserver pgp.mit.edu --send-keys <user-id>

Alternatively, if you use this key on multiple computers, you can export the public key (with new signed expiration dates) and import it on those machines:

$ gpg --export <user-id> > pubkey.gpg
$ gpg --import pubkey.gpg

There is no need to re-export your secret key or update your backups: the master secret key itself never expires, and the signature of the expiration date left on the public key and subkeys is all that is needed.

Rotating subkeys

Warning:Never delete your expired or revoked subkeys unless you have a good reason. Doing so will cause you to lose the ability to decrypt files encrypted with the old subkey. Please only delete expired or revoked keys from other users to clean your keyring.

Alternatively, if you prefer to stop using subkeys entirely once they have expired, you can create new ones. Do this a few weeks in advance to allow others to update their keyring.

Tip: You do not need to create a new key simply because it is expired. You can extend the expiration date, see the section #Extending expiration date.

Create new subkey (repeat for both signing and encrypting key)

$ gpg --edit-key <user-id>
> addkey

And answer the following questions it asks (see #Create a key pair for suggested settings).

Save changes

> save

Update it to a keyserver.

$ gpg --keyserver pgp.mit.edu --send-keys <user-id>

You will also need to export a fresh copy of your secret keys for backup purposes. See the section #Backup your private key for details on how to do this.

Tip: Revoking expired subkeys is unnecessary and arguably bad form. If you are constantly revoking keys, it may cause others to lack confidence in you.

You now need to make your now-revoked key public. If you used a keyserver, send the key to the keyserver. Otherwise, distribute the revoked key to your colleagues.

Signatures

Signatures certify and timestamp documents. If the document is modified, verification of the signature will fail. Unlike encryption which uses public keys to encrypt a document, signatures are created with the user's private key. The recipient of a signed document then verifies the signature using the sender's public key.

Create a signature

Sign a file

To sign a file use the --sign or -s flag:

$ gpg --output doc.sig --sign doc

doc.sig contains both the compressed content of the original file doc and the signature in a binary format, but the file is not encrypted. However, you can combine signing with encrypting.

Clearsign a file or message

To sign a file without compressing it into binary format use:

$ gpg --output doc.sig --clearsign doc

Here both the content of the original file doc and the signature are stored in human-readable form in doc.sig.

Make a detached signature

To create a separate signature file to be distributed separately from the document or file itself, use the --detach-sig flag:

$ gpg --output doc.sig --detach-sig doc

Here the signature is stored in doc.sig, but the contents of doc are not stored in it. This method is often used in distributing software projects to allow users to verify that the program has not been modified by a third party.

Verify a signature

To verify a signature use the --verify flag:

$ gpg --verify doc.sig

where doc.sig is the signed file containing the signature you wish to verify.

If you are verifying a detached signature, both the signed data file and the signature file must be present when verifying. For example, to verify Arch Linux's latest iso you would do:

If a file has been encrypted in addition to being signed, simply decrypt the file and its signature will also be verified.

gpg-agent

gpg-agent is mostly used as daemon to request and cache the password for the keychain. This is useful if GnuPG is used from an external program like a mail client. gnupg comes with systemd user sockets which are enabled by default. These sockets are gpg-agent.socket, gpg-agent-extra.socket, gpg-agent-browser.socket, gpg-agent-ssh.socket, and dirmngr.socket.

The main gpg-agent.socket is used by gpg to connect to the gpg-agent daemon.

The intended use for the gpg-agent-extra.socket on a local system is to set up a Unix domain socket forwarding from a remote system. This enables to use gpg on the remote system without exposing the private keys to the remote system. See gpg-agent(1) for details.

The gpg-agent-browser.socket allows web browsers to access the gpg-agent daemon.

The gpg-agent-ssh.socket can be used by SSH to cache SSH keys added by the ssh-add program. See #SSH agent for the necessary configuration.

The dirmngr.socket starts a GnuPG daemon handling connections to keyservers.

Note: If you use non-default GnuPG #Directory location, you will need to edit all socket files to use the values of gpgconf --list-dirs.

Configuration

gpg-agent can be configured via ~/.gnupg/gpg-agent.conf file. The configuration options are listed in gpg-agent(1). For example you can change cache ttl for unused keys:

~/.gnupg/gpg-agent.conf

default-cache-ttl 3600

Tip: To cache your passphrase for the whole session, please run the following command:

$ /usr/lib/gnupg/gpg-preset-passphrase --preset XXXXX

where XXXXX is the keygrip. You can get its value when running gpg --with-keygrip -K. The passphrase will be stored until gpg-agent is restarted. If you set up default-cache-ttl value, it will take precedence.

Reload the agent

After changing the configuration, reload the agent using gpg-connect-agent:

$ gpg-connect-agent reloadagent /bye

The command should print OK.

However in some cases only the restart may not be sufficient, like when keep-screen has been added to the agent configuration.
In this case you firstly need to kill the ongoing gpg-agent process and then you can restart it as was explained above.

pinentry

gpg-agent can be configured via the pinentry-program stanza to use a particular pinentry user interface when prompting the user for a passphrase. For example:

~/.gnupg/gpg-agent.conf

pinentry-program /usr/bin/pinentry-curses

There are other pinentry programs that you can choose from - see pacman -Ql pinentry | grep /usr/bin/.

Tip: In order to use /usr/bin/pinentry-kwallet you have to install the kwalletcliAUR package.

Cache passwords

max-cache-ttl and default-cache-ttl defines how many seconds gpg-agent should cache the passwords. To enter a password once a session, set them to something very high, for instance:

gpg-agent.conf

max-cache-ttl 60480000
default-cache-ttl 60480000

For password caching in SSH emulation mode, set default-cache-ttl-ssh and max-cache-ttl-ssh instead, for example:

gpg-agent.conf

default-cache-ttl-ssh 60480000
max-cache-ttl-ssh 60480000

Unattended passphrase

Starting with GnuPG 2.1.0 the use of gpg-agent and pinentry is required, which may break backwards compatibility for passphrases piped in from STDIN using the --passphrase-fd 0 commandline option. In order to have the same type of functionality as the older releases two things must be done:

Second, either the application needs to be updated to include a commandline parameter to use loopback mode like so:

$ gpg --pinentry-mode loopback ...

...or if this is not possible, add the option to the configuration:

~/.gnupg/gpg.conf

pinentry-mode loopback

Note: The upstream author indicates setting pinentry-mode loopback in gpg.conf may break other usage, using the commandline option should be preferred if at all possible. [5]

SSH agent

gpg-agent has OpenSSH agent emulation. If you already use the GnuPG suite, you might consider using its agent to also cache your SSH keys. Additionally, some users may prefer the PIN entry dialog GnuPG agent provides as part of its passphrase management.

Set SSH_AUTH_SOCK

You have to set SSH_AUTH_SOCK so that SSH will use gpg-agent instead of ssh-agent. To make sure each process can find your gpg-agent instance regardless of e.g. the type of shell it is child of use pam_env.

Note: If you set your SSH_AUTH_SOCK manually (such as in this pam_env example), keep in mind that your socket location may be different if you are using a custom GNUPGHOME. You can use the following bash example, or change SSH_AUTH_SOCK to the value of gpgconf --list-dirs agent-ssh-socket.

Alternatively, depend on Bash. This works for non-standard socket locations as well:

Note: The test involving the gnupg_SSH_AUTH_SOCK_by variable is for the case where the agent is started as gpg-agent --daemon /bin/sh, in which case the shell inherits the SSH_AUTH_SOCK variable from the parent, gpg-agent[6].

Configure pinentry to use the correct TTY

Also set the GPG_TTY and refresh the TTY in case user has switched into an X session as stated in gpg-agent(1). For example:

Add SSH keys

Once gpg-agent is running you can use ssh-add to approve keys, following the same steps as for ssh-agent. The list of approved keys is stored in the ~/.gnupg/sshcontrol file.

Once your key is approved, you will get a pinentry dialog every time your passphrase is needed. For password caching see #Cache passwords.

Using a PGP key for SSH authentication

You can also use your PGP key as an SSH key. This requires a key with the Authentication capability (see #Custom capabilities). There are various benefits gained by using a PGP key for SSH authentication, including:

Reduced key maintenance, as you will no longer need to maintain an SSH key.

The ability to store the authentication key on a smartcard. GnuPG will automatically detect the key when the card is available, and add it to the agent (check with ssh-add -l or ssh-add -L). The comment for the key should be something like: openpgp:key-id or cardno:card-id.

To retrieve the public key part of your GPG/SSH key, run gpg --export-ssh-key gpg-key.

Unless you have your GPG key on a keycard, you need to add your key to $GNUPGHOME/sshcontrol to be recognized as a SSH key. If your key is on a keycard, its keygrip is added to sshcontrol implicitly. If not, get the keygrip of your key this way:

GnuPG only setups

If you do not plan to use other cards but those based on GnuPG, you should check the reader-port parameter in ~/.gnupg/scdaemon.conf. The value '0' refers to the first available serial port reader and a value of '32768' (default) refers to the first USB reader.

GnuPG with pcscd (PCSC Lite)

pcscd(8) is a daemon which handles access to smartcard (SCard API). If GnuPG's scdaemon fails to connect the smartcard directly (e.g. by using its integrated CCID support), it will fallback and try to find a smartcard using the PCSC Lite driver.

To use pscsd installpcsclite and ccid. Then start and/or enablepcscd.service. Alternatively start and/or enable pcscd.socket to activate the daemon when needed.

Always use pcscd

If you are using any smartcard with an opensc driver (e.g.: ID cards from some countries) you should pay some attention to GnuPG configuration. Out of the box you might receive a message like this when using gpg --card-status

gpg: selecting openpgp failed: ec=6.108

By default, scdaemon will try to connect directly to the device. This connection will fail if the reader is being used by another process. For example: the pcscd daemon used by OpenSC. To cope with this situation we should use the same underlying driver as opensc so they can work well together. In order to point scdaemon to use pcscd you should remove reader-port from ~/.gnupg/scdaemon.conf, specify the location to libpcsclite.so library and disable ccid so we make sure that we use pcscd:

Shared access with pcscd

GnuPG scdaemon is the only popular pcscd client that uses PCSC_SHARE_EXCLUSIVE flag when connecting to pcscd. Other clients like OpenSC PKCS#11 that are used by browsers and programs listed in Electronic identification are using PCSC_SHARE_SHARED that allows simultaneous access to single smartcard. pcscd will not give exclusive access to smartcard while there are other clients connected. This means that to use GnuPG smartcard features you must before have to close all your open browser windows or do some other inconvenient operations. There is a out of tree patch in GPGTools/MacGPG2 git repo that enables scdaemon to use shared access but GnuPG developers are against allowing this because when one pcscd client authenticates the smartcard then some other malicious pcscd clients could do authenticated operations with the card without you knowing. You can read full mailing list thread here.

If you accept the security risk then you can use the patch from GPGTools/MacGPG2 git repo or use gnupg-scdaemon-shared-accessAUR package. After patching your scdaemon you can enable shared access by modifying your scdaemon.conf file and adding shared-access line end of it.

Multi applet smart cards

When using YubiKeys or other multi applet USB dongles with OpenSC PKCS#11 may run into problems where OpenSC switches your Yubikey from OpenPGP to PIV applet, breaking the scdaemon.

You can hack around the problem by forcing OpenSC to also use the OpenPGP applet. Open /etc/opensc.conf file, search for Yubikey and change the driver = "PIV-II"; line to driver = "openpgp";. If there is no such entry, use pcsc_scan. Search for the Answer to Reset ATR: 12 34 56 78 90 AB CD .... Then create a new entry.

In the latest version of GnuPG, the default algorithms used are SHA256 and AES, both of which are secure enough for most people. However, if you are using a version of GnuPG older than 2.1, or if you want an even higher level of security, then you should follow the above step.

Encrypt a password

It can be useful to encrypt some password, so it will not be written in clear on a configuration file. A good example is your email password.

First create a file with your password. You need to leave one empty line after the password, otherwise gpg will return an error message when evaluating the file.

Revoking a key

Key revocation should only be performed if your key is compromised or lost, or you forget your passphrase.

Revocation certificates are automatically generated for newly generated keys, although one can be generated manually by the user later. These are located at ~/.gnupg/openpgp-revocs.d/. The filename of the certificate is the fingerprint of the key it will revoke.

To revoke your key, simply import the revocation certificate:

$ gpg --import <fingerprint>.rev

Then send the key that was revoked back to your keyserver(s) of choice.

Hide all recipient id's

By default the recipient's key ID is in the encrypted message. This can be removed at encryption time for a recipient by using hidden-recipient <user-id>. To remove it for all recipients add throw-keyids to your configuration file. This helps to hide the receivers of the message and is a limited countermeasure against traffic analysis. (Using a little social engineering anyone who is able to decrypt the message can check whether one of the other recipients is the one he suspects.) On the receiving side, it may slow down the decryption process because all available secret keys must be tried (e.g. with --try-secret-key <user-id>).

Using caff for keysigning parties

To allow users to validate keys on the keyservers and in their keyrings (i.e. make sure they are from whom they claim to be), PGP/GPG uses the Web of Trust. Keysigning parties allow users to get together at a physical location to validate keys. The Zimmermann-Sassaman key-signing protocol is a way of making these very effective. Here you will find a how-to article.

For an easier process of signing keys and sending signatures to the owners after a keysigning party, you can use the tool caff. It can be installed from the AUR with the package caff-gitAUR.

To send the signatures to their owners you need a working MTA. If you do not have already one, install msmtp.

Always show long ID's and fingerprints

To always show long key ID's add keyid-format 0xlong to your configuration file. To always show full fingerprints of keys, add with-fingerprint to your configuration file.

Custom capabilities

For further customization also possible to set custom capabilities to your keys. The following capabilities are available:

Sign - allows the key to create cryptographic signatures that others can verify with the public key.

Encrypt - allows anyone to encrypt data with the public key, that only the private key can decrypt.

Authenticate - allows the key to authenticate with various non-GnuPG programs. The key can be used as e.g. an SSH key.

It's possible to specify the capabilities of the master key, by running:

$ gpg --full-generate-key --expert

And select an option that allows you to set your own capabilities.

Comparably, to specify custom capabilities for subkeys, add the --expert flag to gpg --edit-key, see #Edit your key for more information.

Troubleshooting

Not enough random bytes available

When generating a key, gpg can run into this error:

Not enough random bytes available. Please do some other work to give the OS a chance to collect more entropy!

To check the available entropy, check the kernel parameters:

$ cat /proc/sys/kernel/random/entropy_avail

A healthy Linux system with a lot of entropy available will have return close to the full 4,096 bits of entropy. If the value returned is less than 200, the system is running low on entropy.

To solve it, remember you do not often need to create keys and best just do what the message suggests (e.g. create disk activity, move the mouse, edit the wiki - all will create entropy). If that does not help, check which service is using up the entropy and consider stopping it for the time. If that is no alternative, see Random number generation#Alternatives.

su

When using pinentry, you must have the proper permissions of the terminal device (e.g. /dev/tty1) in use. However, with su (or sudo), the ownership stays with the original user, not the new one. This means that pinentry will fail, even as root. The fix is to change the permissions of the device at some point before the use of pinentry (i.e. using gpg with an agent). If doing gpg as root, simply change the ownership to root right before using gpg:

# chown root /dev/ttyN # where N is the current tty

and then change it back after using gpg the first time. The equivalent is likely to be true with /dev/pts/.

Note: The owner of tty must match with the user for which pinentry is running. Being part of the group ttyis not enough.

Tip: If you run gpg with script it will use a new tty with the correct ownership:

mutt

Mutt might not use gpg-agent correctly, you need to set an environment variableGPG_AGENT_INFO (the content does not matter) when running mutt. Be also sure to enable password caching correctly, see #Cache passwords.

"Lost" keys, upgrading to gnupg version 2.1

When gpg --list-keys fails to show keys that used to be there, and applications complain about missing or invalid keys, some keys may not have been migrated to the new format.

Please read GnuPG invalid packet workaround. Basically, it says that there is a bug with keys in the old pubring.gpg and secring.gpg files, which have now been superseded by the new pubring.kbx file and the private-keys-v1.d/ subdirectory and files. Your missing keys can be recovered with the following commnads:

gpg hanged for all keyservers (when trying to receive keys)

If gpg hanged with a certain keyserver when trying to receive keys, you might need to kill dirmngr in order to get access to other keyservers which are actually working, otherwise it might keeping hanging for all of them.

Smartcard not detected

Your user might not have the permission to access the smartcard which results in a card error to be thrown, even though the card is correctly set up and inserted.

One possible solution is to add a new group scard including the users who need access to the smartcard.

One needs to adapt VENDOR and MODEL according to the lsusb output, the above example is for a YubikeyNEO.

server 'gpg-agent' is older than us (x < y)

This warning appears if gnupg is upgraded and the old gpg-agent is still running. Restart the user's gpg-agent.socket (i.e., use the --user flag when restarting).

IPC connect call failed

The factual accuracy of this article or section is disputed.

Reason: The gpg-agent*.socket systemd sockets provided by the gnupg package create the sockets in /run/user/$UID/gnupg/ which is guaranteed to be an appropriate file system. (Discuss in Talk:GnuPG#)

Make sure gpg-agent and dirmngr are not running with killall gpg-agent dirmngr and the $GNUPGHOME/crls.d/ folder has permission set to 700.

If your keyring is stored on a vFat filesystem (e.g. a USB drive), gpg-agent will fail to create the required sockets (vFat does not support sockets), you can create redirects to a location that handles sockets, e.g. /dev/shm: